Add API to support key remappings on native side

For adding support for modifier key remapping, we need to add
native support save key remappings and send appropriate android
key codes using KeyCharacterMap.

Test: atest KeyboardLayoutChangeTest
Bug: 252812993
Change-Id: Ib3efa866c6e6408dd11e97dfaf49feb92f48bc18
diff --git a/services/inputflinger/tests/fuzzers/MapperHelpers.h b/services/inputflinger/tests/fuzzers/MapperHelpers.h
index 445ed18..cd852d6 100644
--- a/services/inputflinger/tests/fuzzers/MapperHelpers.h
+++ b/services/inputflinger/tests/fuzzers/MapperHelpers.h
@@ -211,6 +211,7 @@
     int32_t getSwitchState(int32_t deviceId, int32_t sw) const override {
         return mFdp->ConsumeIntegral<int32_t>();
     }
+    void addKeyRemapping(int32_t deviceId, int32_t fromKeyCode, int32_t toKeyCode) const override {}
     int32_t getKeyCodeForKeyLocation(int32_t deviceId, int32_t locationKeyCode) const override {
         return mFdp->ConsumeIntegral<int32_t>();
     }